Unit 4

Question 1

traveling wave

Answer 1

A wave that propagates through space

Question 2

standing wave

Answer 2

A wave that vibrates in a fixed region, has boundary conditions

Question 3

fundamental

Answer 3

n=1, standing waves with the fewest nodes

Question 4

de Broglie wavelength for matter waves

Answer 4

λ=h/mv (mv=momentum, kg/s)

Question 4

node

Answer 4

-A region of no vibration (of zero amplitude) of a standing wave
-the higher the n, the more numerous the nodes, the shorter the wavelength, the higher the frequency, the higher the energy

Question 5

Heisenberg uncertainty principle

Answer 5

∆x∆p > h/4π

Question 6

∆x

Answer 6

uncertainty in x, position

Question 7

∆p

Answer 7

uncertainty in p, momentum (mv)

Question 8

uncertainty ∆

Answer 8

full width half max of probability curve

Question 9

observe particle nature

Answer 9

measure position, small ∆x, large ∆p

Question 10

observe wave nature

Answer 10

diffraction or interference, small ∆p, large ∆x

Question 11

indeterminate

Answer 11

If an observable property does not have a definite value under certain experimental conditions, it is said to be indeterminate

Question 12

wave packet

Answer 12

-a group of superposed waves which together form a traveling localized disturbance, especially one described by Schrödinger’s equation and regarded as representing a particle
-can broaden with time or collapse upon measurement

Question 13

how something appears depending on what experiment we do

Answer 13

cannot observe both wave and particle nature at same time

Question 14

Amplitude (Ψ)

Answer 14

Ψ(x)= Amax(sin(2πx/λ))

Question 15

Probability

Answer 15

Ψ^2

Question 16

Uncertainty principle

Answer 16

-position (x) and momentum (p) cannot be determined exactly at same time
-there is a limit to the precision with which certain pairs of physical properties, such as position and momentum, can be simultaneously known

Question 17

Quantum weirdness

Answer 17

-a qm particle (ex. an electron) is described by a wave function (amplitude vs position), Ψ(x)
-qm particle can exist as a superposition of “possibility” states described by a wave
-Amplitude= wave1 + wave2 + wave3…

Question 18

Before a measurement

Answer 18

Ψ(x)= Ψ1(x) + Ψ2(x) + Ψ3(x) (superposition)

Question 19

After a measurement

Answer 19

Ψ(x)= Ψi(x), where i=1, 2, 3, … (no superposition)

Question 20

Complementary principle

Answer 20

-some experiments always detect the wave nature of wave particles, while others always detect the particle nature
-no experiment can detect both